Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dua tren » dung tren
dau tren » dau tien, dat tren, dau tieng
so sach » so sanh, bo sach, hoc sach
co sach » bo sach, cuon sach, hoc sach
nang xa » nang x, lang xa, nang ma
ha truc » ba truc, ha thuc, hang truc
truc va » thuc va, thuc vat, trung va
va doan » va doanh, van doan, va dan
doan vi » doan va, don vi, doan thi
van ha » van hoa, van chat, van hanh

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((so sach) OR (co sach)) ky nang xa hoi. hieu van ha truc va doan vi ((dua tren) or (dau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (co sach)) ky nang xa hoi. hieu van ha truc va doan vi ((dua tren) OR (dau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) OR (co sach)) ky nang xa hoi. hieu van ha truc va doan vi ((dua tren) or (dau tren))".
• Adding a wildcard symbol may retrieve word variants: ((so sach) OR (co sach)) ky nang xa hoi. hieu van ha truc va doan vi ((dua tren) or (dau tren))*.